Parasitism

Ecclesiastes 3:1-8

' TO EVERYTHING there is a season, and a time for every matter or purpose under heaven: A time to be born and a time to die, a time to plant and a time to pluck up what is planted, [Heb. 9:27.] A time to kill and a time to heal, a time to break down and a time to build up, A time to weep and a time to laugh, a time to mourn and a time to dance, A time to cast away stones and a time to gather stones together, a time to embrace and a time to refrain from embracing, A time to get and a time to lose, a time to keep and a time to cast away, A time to rend and a time to sew, a time to keep silence and a time to speak, [Amos 5:13.] A time to love and a time to hate, a time for war and a time for peace. [Luke 14:26.]'

Parasitism is a close relationship where one organism (the parasite) benefits by living on or in another organism (the host), taking nutrients and causing harm, but usually not killing it immediately, allowing for continued feeding. Examples include fleas on dogs, tapeworms in humans, and mosquitoes, where the parasite gains resources, weakening the host or transmitting disease, with hosts evolving defenses like grooming or medicine. 

Key Characteristics:

• Beneficiary: The parasite gains food, shelter, or other resources.

• Victim: The host suffers harm, disease, or loss of nutrients.

• Adaptation: Parasites often have specialized features, like a tapeworm lacking a digestive system because it lives in the host's gut.

• Survival: They typically need the host to survive and reproduce, so they avoid killing it too quickly. 

Examples of Parasites:

• Ectoparasites (outside): Fleas, ticks, lice that live on the skin.

• Endoparasites (inside): Tapeworms, hookworms, protozoa in the digestive system or blood.

• Brood Parasites: Cuckoos and cowbirds that lay eggs in other birds' nests.

• Plants: Mistletoe taking nutrients from trees. 

Transmission:

• Direct Contact: Lice passing through physical touch.

• Vectors: Mosquitoes carrying malaria parasites.

• Resistant Stages: Larvae or cysts surviving in the environment.

• Intermediate Hosts: Some parasites need a secondary organism in their life cycle (e.g., tapeworms). 

Impact:

• Causes disease and weakens hosts.

• Can significantly impact populations and ecosystems.

• Drives evolution through host-parasite arms races (hosts developing defenses, parasites evolving to overcome them).